Business Segments (Reconciliation of Assets from Segment to Consolidated) (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Assets	$ 393,010	$ 393,023
Rail Products and Services
Segment Reporting Information [Line Items]
Assets	186,588	174,049
Construction Products
Segment Reporting Information [Line Items]
Assets	81,953	81,074
Tubular and Energy Services
Segment Reporting Information [Line Items]
Assets	99,076	100,006
Unallocated corporate assets
Segment Reporting Information [Line Items]
Assets	$ 25,393	$ 37,894